In recent years, although portable wireless equipments such as portable telephones have been widely spread, various types of the portable telephones have been developed. Among the various types of the portable telephones, compact folding-types have been widely used in each of which upper and lower cases are folded in an unused state thereby to enhance the portability. Such a portable telephone has the structure capable of changing its configuration in accordance with a using state, so that it is important to secure the antenna performance in each of opened and closed states. In such a folding-type portable telephone, the miniaturization and the multi-functioning have been advanced. As the multi-functioning in recent years, the improvement of design and the differentiation from other portable telephones have been advanced. As one of the demands requested in such the multi-functioning, there is the antenna configuration having no projection. Further, a new design having no conventional mechanical hinge structure has been requested in the meaning of the differentiation. Conventionally, in the folding-type portable telephone, the following three configurations are generally known as the configuration for obtaining good antenna performance in each of the opened and closed states.
The first configuration of the folding-type portable telephone is arranged in a manner that a projection type antenna is mounted on the hinge side of the lower case. A helical antenna or an extensible monopole antenna is generally used as the projection type antenna. In the opened state, the antenna acts as a resonance element which vibrates the upper case, whereby the entirety of the portable telephone operates as the dipole antenna in which an upper board and a lower board act as a radiation element. Further, since the antenna portion protrudes from the case, the antenna gain can be made high advantageously in a state where the portable telephone is held by a hand. Furthermore, in the closed state, the wavelength is shortened by the radiation element such as the helical antenna, so that the telephone operates as the monopole antenna of λ/4.
The second configuration of the folding-type portable telephone is arranged in a manner that the antenna is contained within the case thereby to eliminate the projection portion, that is, for example, an L-shaped antenna or a reverse F-shaped antenna etc. is mounted within the case. Such an antenna operates in a state of being completely housed within the case.
The third configuration of the folding-type portable telephone is arranged to apply the operation theory of the first configuration in a manner that the antenna is mounted on the hinge side of the lower case thereby to use the upper case as the radiation element in the opened state. That is, the antenna is configured so as to have no projection and the upper case is directly vibrated thereby to use as the radiation element in the opened state.
FIG. 5 is a diagram showing the schematic configuration of a folding-type portable telephone described in a patent document 1, in which (a) shows an opened state and (b) shows a closed state.
As shown in FIG. 5, the folding-type portable telephone described in the patent document 1 is arranged in a manner that an upper case 1 and a lower case 2 are coupled via a hinge portion 3 to each other so as to be foldable. The upper case 1 is provided with a shield box 4 for shielding a circuit board contained therein, and the shield box 4 also has the function of an antenna. The lower case 2 is provided with a shield box 5 for shielding a circuit board on which a transmission circuit 6 etc. are formed. The transmission circuit 6 is coupled to the shield box 4 of the upper case 1 via a flexible board 7 housed within the hinge portion 3. According to this configuration, since there is no height limitation in the case from which radio wave is radiated and the entirety of the case can be made large as an effective area of the antenna, the antenna performance of a large band and a high gain can be obtained.
Patent Document 1: JP-A-2002-335180